In modern day turbomachines, such as a gas turbine, various parts of the turbomachine operate at very high temperatures. These turbomachine parts, such as a blade or a vane, typically include an airfoil portion and a root portion separated by a platform. The high temperatures during operation of the turbomachine may cause damage to the turbomachine part or its constituents, hence cooling of the turbomachine part is important. Cooling of these parts is generally achieved by passing a cooling fluid that may include air from a compressor of the turbomachine through a core passage way cast into the turbomachince part, for example cooling passage ways formed inside the airfoil of the blade.
Thus, the airfoil portion of the turbomachine part, for example a blade, is cooled by directing a cooling fluid to flow through passages formed in the airfoil portion of the turbomachine part.
However, adequate cooling of the platform of the turbomachine part is difficult since cooling air is generally not utilized in cooling the entire platform. Regions of the platform such as an airfoil side of the platform, i.e. a side of the platform from which the airfoil emerges, are exposed to hot gases originating from the combustors. Normally, cooling of the platform is achieved by providing film cooling on the airfoil side of the platform. However, the cooling of the airfoil side is insufficient to adequately cool other regions of the platform especially a root side of the platform, i.e. a side of the platform from which the root emerges. This insufficiency results in oxidation and cracking in the platform, and subsequently reduction of the life span of the turbomachine part.
From US 2009/016881 A1 an arrangement is known in which improved cooling of a platform region and the transition region from a turbine blade to a platform of a turbine blade is provided, thus ensuring the cooling of the delimitation of a flow channel in a gas turbine. To achieve this, the platform includes a first platform wall that does not support the vane and a second platform wall that supports the vane with a hollow space in between. At the root of the vane and over the course of the transition region from the turbine blade to the platform, the first platform wall is aerodynamically curved and the course of the second platform wall has a receding shoulder in relation to the first platform wall, as a continuation of the vane.